Workers in certain hazardous professions, such as emergency rescue workers and military personnel, may in certain circumstances deal with various chemical or biological agents, the inhalation of which, or exposure to which, can be irritating, health-threatening, or even life-threatening. Members of those professions have benefited from the development of hoods and escape mask systems designed to protect the wearer by providing a physical barrier between the wearer and the external environment, and thus preventing chemical or biological threats from contacting the wearer. Such hoods and masks are generally fluid- and air-tight, at least partially envelope the wearer's head, and interface with the wearer's neck. The effectiveness of such hoods and masks in providing complete protection to the wearer depends in part on the ability of one portion of the hood or mask, the neck dam, to form an adequately sound seal about the wearer's neck.
A neck dam is a structure surrounding an opening in a protective hood or mask through which a wearer inserts his or her head into the hood or mask. The neck dam, typically constructed of an elastic or resilient material, is generally smaller in diameter than the head of the wearer, and can be stretched so that the wearer can insert his or her head into the hood. When released, the neck dam contracts and thus becomes positioned proximate to and generally against the wearer's neck, often forming a seal that prevents the entry of gases or agents from the external environment into the hood.
Traditionally, a neck dam relies on the elasticity of the material from which it is constructed to create the seal about the wearer's neck. This construction has certain limitations and drawbacks. For example, the elastic material chosen for use in traditional neck dams may not conform to the physical dimensions of a wearer's neck. In the case of a wearer with a larger diameter neck, the dam may be too tight, possibly leading to shortness of breath and reduced blood flow to the brain due to the pressure of the neck dam on the individual's windpipe and carotid arteries. In the case of a wearer with a smaller diameter neck, the neck dam may be too loose, and thus compromise the quality of the desired seal. When there is not enough sealing pressure to provide an adequate seal around the wearer's neck, movements of the head, such as looking upward or downward, can cause the neck dam to leak, permitting chemical or biological agents to enter the hood or mask.
Accordingly, there is a need for a device and method that may improve the level of protection and/or the level of comfort afforded by neck dams of chemical and biological hoods and escape mask systems.